<template>
  <el-select
    :title="multiple ? optionData.name : ''"
    ref="select"
    :value="value"
    placeholder="请选择"
    :size="size"
    clearable
    :disabled="disabled"
    :filterable="filterable"
    :filter-method="filterMethod"
    :style="{ ...style, width: '100%' }"
    @clear="clear"
    @visible-change="visibleChange"
  >
    <el-option
      ref="option"
      class="tree-select__option"
      :value="optionData.id"
      :label="optionData.name"
    >
      <el-tree
        ref="tree"
        class="tree-select__tree"
        :class="`tree-select__tree--${multiple ? 'checked' : 'radio'}`"
        :node-key="nodeKey"
        :data="data"
        :props="props"
        :default-expanded-keys="[value]"
        :show-checkbox="multiple"
        :highlight-current="!multiple"
        :expand-on-click-node="multiple"
        :filter-node-method="filterNode"
        @node-click="handleNodeClick"
        @check-change="handleCheckChange"
      ></el-tree>
    </el-option>
  </el-select>
</template>

<script>
export default {
  name: "TreeSelect",
  props: {
    style: {
      type: Object,
      default: {},
    },
    size: {
      type: Object,
      default: "mini",
    },
    // v-model绑定
    value: {
      type: [String, Number],
      default: "",
    },
    multiple: {
      type: Boolean,
      default: false,
    },
    // 树形的数据
    data: {
      type: Array,
      default: function () {
        return [];
      },
    },
    // 每个树节点用来作为唯一标识的属性
    nodeKey: {
      type: [String, Number],
      default: "id",
    },
    filterable: {
      type: Boolean,
      default: false,
    },
    disabled: {
      type: Boolean,
      default: false,
    },
    // tree的props配置
    props: {
      type: Object,
      default: function () {
        return {
          label: "label",
          children: "children",
        };
      },
    },
  },
  data() {
    return {
      optionData: {
        id: "",
        name: "",
      },
      filterFlag: false,
    };
  },
  watch: {
    value: {
      handler(val) {
        if (!this.isEmpty(this.data)) {
          this.init(val);
        }
      },
      immediate: true,
    },
    data: function (val) {
      if (!this.isEmpty(val)) {
        this.init(this.value);
      }
    },
  },
  created() {},
  methods: {
    // 是否为空
    isEmpty(val) {
      for (let key in val) {
        return false;
      }
      return true;
    },
    handleNodeClick(data) {
      if (this.multiple) {
        return;
      }
      if (data.children && data.children.length == 0) {
        this.$emit("input", data[this.nodeKey]);
        this.$refs.select.visible = false;
      }
    },
    handleCheckChange() {
      const nodes = this.$refs.tree.getCheckedNodes();
      const value = nodes.map((item) => item[this.nodeKey]).join(",");
      this.$emit("input", value);
    },
    init(val) {
      // 多选
      if (this.multiple) {
        const arr = val.toString().split(",");
        this.$nextTick(() => {
          this.$refs.tree.setCheckedKeys(arr);
          const nodes = this.$refs.tree.getCheckedNodes();
          this.optionData.id = val;
          this.optionData.name = nodes
            .map((item) => item[this.props.label])
            .join(",");
        });
      }
      // 单选
      else {
        val = val === "" ? null : val;
        this.$nextTick(() => {
          this.$refs.tree.setCurrentKey(val);
          if (val === null) {
            return;
          }
          const node = this.$refs.tree.getNode(val);
          this.optionData.id = val;
          this.optionData.name = node.label;
        });
      }
    },
    visibleChange(e) {
      if (e) {
        const tree = this.$refs.tree;
        this.filterFlag && tree.filter("");
        this.filterFlag = false;
        let selectDom = null;
        if (this.multiple) {
          selectDom = tree.$el.querySelector(".el-tree-node.is-checked");
        } else {
          selectDom = tree.$el.querySelector(".is-current");
        }
        setTimeout(() => {
          this.$refs.select.scrollToOption({ $el: selectDom });
        }, 0);
      }
    },
    clear() {
      this.$emit("input", "");
    },
    filterMethod(val) {
      this.filterFlag = true;
      this.$refs.tree.filter(val);
    },
    filterNode(value, data) {
      if (!value) return true;
      const label = this.props.label || "name";
      return data[label].indexOf(value) !== -1;
    },
  },
};
</script>

<style lang="scss">
.tree-select__option {
  &.el-select-dropdown__item {
    height: auto;
    line-height: 1;
    padding: 0;
    background-color: #fff;
  }
}

:v-deep.el-input--mini .el-input__inner {
  height: 100% !important;
  line-height: 100% !important;
}

.tree-select__tree {
  padding: 4px 20px;
  font-weight: 400;

  &.tree-select__tree--radio {
    .el-tree-node.is-current > .el-tree-node__content {
      color: #204ec4;
      font-weight: 700;
    }
  }
}
</style>
